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RESCHEDULED - PGI Colloquium:

Prof. Dr. Andreas Heinrich, Ewha Womans University & IBS Center for Quantum Nanoscience, Seoul, Korea


Online Talk

Please note: You will receive the link to the online talk in the e-mail invitation, usually sent out a few days before the lecture takes place. It is also available on request from the contact person below.

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18 Jun 2021 11:00

Electron Spin Resonance of Individual Spins on a Surface

BildCopyright: Prof. Dr. Heinrich

Scanning Tunneling Microscopy (STM) can be combined with electron spin resonance [1]. The major advantage of spin resonance is the fact that the energy resolution is independent of the temperature and thus can be much higher than a Fermi-function limited spectroscopy technique such as STM tunneling. In ESR STM we apply a microwave-frequency electric field to the STM tunnel junction and convert this AC electric field into a driving field for the ESR. We find an energy resolution, which is about 10,000 times better than low-temperature STM. Two advantages of ESR STM over ensemble-averaging techniques are first, the obvious fact that individual spin systems are measured and second, that this can be combined with precise atom manipulation to build engineered nanostructures.

We will begin by introducing the basic concepts of STM, which might be new to some members of this community. Then we will focus on two examples of ESR STM. First, we will utilize the atomic spin of Ti-H molecules which are adsorbed on thin MgO films supported on Ag metal substrates. Ti is a beautiful example since it has a spin of S=1/2 in this configuration together with a rich isotope distribution including nuclear spins [2].

In the second example we will take ESR STM from the coherent manipulation of a single spin to the resonant control of 2 coupled spins. This important step allows us to perform double resonance experiments (ELDOR), in which we independently and coherently drive both spins in a weakly coupled dimer. A model reveals the complex spin dynamics and allows us to extract the Rabi rate and the spin relaxation time for the remote spin as well as for the one under the tip [Unpublished]. Taken together with the recent advance towards pulsed ESR STM, it might be possible to implement quantum information on coupled spins on surfaces.

ESR STM is just in its infancy with many groups joining this research effort. I believe that this technique will occupy a bright corner of quantum-coherent nanoscience.

  1. Susanne Baumann, William Paul, Taeyoung Choi, Christopher P. Lutz, Arzhang Ardavan, Andreas J. Heinrich, “Electron Paramagnetic Resonance of Individual Atoms on a Surface”, Science 350, 417 (2015)

  2. Philip Willke, Yujeong Bae, Kai Yang, Jose L. Lado, Alejandro Ferrón, Taeyoung Choi, Arzhang Ardavan, Joaquín Fernández-Rossier, Andreas J. Heinrich and Christopher P. Lutz, “Hyperfine interaction of individual atoms on a surface”, Science 362, 336 (2018)

Support from Institute for Basic Science (IBS-R027-D1) is gratefully acknowledged.

Contact

Prof. Dr. Markus Ternes
Phone: +49 2461 61-6381
email: m.ternes@fz-juelich.de